Elucidating sulfate radical-mediated disinfection profiles and mechanisms of Escherichia coli and Enterococcus faecalis in municipal wastewater.

Document Type

Article

Publication Date

4-15-2020

Department

Department of Civil, Environmental, and Geospatial Engineering

Abstract

Practical applications of disinfection technologies for engineered waters require an in‒depth under-standing of disinfection profiles and mechanisms of pathogenic bacteria in a complex matrix. This study investigated the inactivation of E. coli and E. faecalis by SO-4, an emerging advanced disinfectant, in ultra pure water (UPW) and wastewater effluent (WE). Based on the bacterial inactivation kinetics in UPW in a zerovalent iron/peroxydisulfate system, the second order rate constants (k) for SO-4 reacting with E. coliand E. faecalis were measured to be (1.39±0.1) x 109 M-1 s-1 and (6.71±0.1) x 109 M-1 s-1,respectively. The morphological images of both bacteria by the scanning electron microscope indicated that SO-4 initiates oxidative reactions on the wall/membranes, causing their irreversible damage, ultimately affecting membrane permeability and physiological functions. To profile the inactivation kinetics of two strains of bacteria in WE matrix, a mechanistic process‒based model with the obtained k values was developed. Sensitivity and uncertainty analyses indicated that the key parameters for the model predictions were the concentrations of halide ions (i.e.,Br- and Cl-) in WE and their k values reacting with SO-4 accounting for>80% of uncertainty or variance expected in predicted bacterial inactivation.This model allows precise estimation of required disinfectant dose even in complex water matrices,shedding lights on the extension of application of SO-4‒ based technology in wastewater treatments.

Publication Title

Water research

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